A possible definition of life.

James Foster foster at skink.cs.uidaho.edu
Thu Apr 24 11:12:42 EST 1997


In article <m0wKJBc-0000feC at uctmail.uct.ac.za> ed at MOLBIOL.UCT.AC.ZA ("Ed Rybicki") writes:


   So does any definition requiring that a living thing code for itself 
   AND replicate itself.

   > Life does what it chooses to, when it chooses to, and how it chooses to do
   > it. 
   > Can anybody think of a living creature, (agreed upon beforehand) that
   > doesn't obey this rule. 

Well...I think this rules me out as a living thing.  After all, I
can't replicate myself.  The best I can do is to work with another
organism (my wife) and generate something completely different but
somewhat similar (my kids).  Even then, my wife doesn't do the all the
work.  Ribosomes and such do the work.  

What really replicates here, me or my DNA (and my wife's)?  Does this
definition make the DNA alive, but leave me as an unliving
repository...like a copying machine?

Also, what does it mean to "code for itself"?  DNA is not a computer
program.  The sequence does NOT code for an individual.  The
"blueprints" must also include: DNA structure, RNA structure, cell
environment (a very big deal), and more I'm sure.  As geeks we like to
think of computer programs as the model for life...but I suggest that
this is as much an illusion as the "world is a clock" metaphor of the
1700s.  

-- 
James A. Foster			email: foster at cs.uidaho.edu
Laboratory for Applied Logic	Dept. of Computer Science
University of Idaho		http://www.cs.uidaho.edu/~foster

pgp key available at: ftp://ftp.cs.uidaho.edu/pub/foster/pgp-key.asc



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